Recently, and by applying a highly sensitive immunological approach to the study of gene expression in the neural retina, we identified four immunologically distinct protein bands (MW 23, 33, 55, and 69 kD) which are present in the normal adult retinas of human, cow, rat and mouse; but are missing from the rodless retinas of adult mutant mice homozygous for the retinal degeneration (rd) gene. Moreover, none of the protein bands of interest is found in non-retinal eye parts, non-neural tissues or CNS and PNS neural tissues. From postnatal developmental studies of age-matched normal and mutant congenic mice, the temporal appearance and disappearance of the four retinal specific protein bands coincides with the morphological maturation and degeneration of the photoreceptor cell population. It is the major objective of this research plan to generate the appropriate cDNA probes that will be applied to the detailed analysis of the expression of one or more of the genes for the retinal specific proteins under normal and genetically programmed degenerating conditions. Beginning with the 23 kD protein, and using monospecific antibodies and retinal cDNA expression libraries from this laboratory, the 23 kD cDNA will be cloned. In a parallel approach, the 23 kD protein will be purified from retina, its amino acid sequence determined and specific oligonucleotide probes will be made and used for identifying the corresponding cDNA clones. The cloned cDNA's will be characterized and the identity of the protein coded for confirmed. Using the antibody and/or cDNA probes respectively, it will be possible to determine whether the retinal specific proteins are photoreceptor specific proteins or whether any one or more of these proteins is differentially expressed by other retinal cells in response to an "inductive regulatory" influence of the photoreceptor cells. With these complementary probes it will be further possible to quantitate, characterize and isolate the messenger RNA"s coding for these retinal specific proteins. It is anticipated that the results and probes obtained will provide for the detailed examination of the expression of the genes coding for the identified retinal specific proteins during normal retinal development and during the genetically programmed degeneration of photoreceptor cells that occurs in mice with hereditary blindness.